The Capellan Reserve Cavalry formed during the years between the repeal of the Star LeagueCouncil Edict of 2650 in 2572 and the eruption of the Amaris Coup. The Capellan Confederation Armed Forces had expanded rapidly, as did the militaries of the other Great Houses, and the Capellan Reserve Cavalry was the last of the CCAFbrigades to form (or re-form) prior to the Coup. Between 2572 and 2765 the Reserve Cavalry mustered seven new regiments, with the intention that the Reserve Cavalry would act as rapid reinforcements to other units and as a source of replacement personnel for frontline commands. Like the other regiments within the Reserve Cavalry, the Fourth Confederation Reserve Cavalry was an odd combination of volunteer corps, training cadre and militia, with standing orders for the junior Colonel in charge of the Fourth to subordinate his command to place it at the full disposal of any frontline command it served alongside. This allowed the Fourth to act as a synergistic part of the superior formation, free of internal power-struggles or conflicts.[1]

The Fifth was formed using recruits from the new colony worlds in the Confederation's rimward regions, and the majority of the recruits were hardy pioneers accustomed to extended periods of isolation, harsh environments and privation.[1]

The Fourth Confederation Reserve Cavalry fought Wolf's Dragoons on Styk in late 3006 and early 3007.[3] When Wolf’s Dragoons launched a raid on the 'Mech construction facility at Hegemony Bay on the planet Styk in late 3006 they were met by the Fourth Reserve. The Dragoons used a diversionary attack on a nearby dam to lure the 4th Reserve away from defense of the facility. When the unit returned they engaged hover units of the Dragoons and eventually pushed their way back into the city but not after heavy damage was inflicted.[3]

The Screaming Eagles mercenary force occupied New Canton and battled with the First Battalion of the 4th Reserve and the Third Battalion of Trimaldi's Secutors in guerrilla-style engagements in the jungles of the northern continent. When the Eagles finally caught up with the 4th Reserve and cornered them up against a river the unit surrendered. After the surrender the commander of the Eagles, Colonel Opson Mathis, ordered the 'Mechs of the Fourth Reserve disabled, sealed the pilots in their cockpits, and murdered them by pushing them into the river.[5]

By the end of the Fourth Succession War two of the Fourth's battalions had been destroyed and a third not engaged.[6] At some point after this they were disbanded and were only reconstituted sometime between 3113 and 3134.

As of 3145 during their operations with Warrior House Hiritsu, the Fourth CRC would divide the regiment into two flanking columns and attempt to envelope enemy formations. This allowed for them to pin those formations on to Warrior House Hiritsu to destroy.[2]